Spenser Heaps, Deseret News
Republican John Curtis gives his victory speech at an election night party at the Marriott Hotel in Provo on Tuesday, Nov. 7, 2017. Curtis won the special election to fill the 3rd Congressional District seat. Congressman-elect John Curtis's lead over his opponents in the 3rd District grew slightly in the latest results released Thursday, confirming that he's the winner of the special election.

SALT LAKE CITY — Congressman-elect John Curtis' lead over his opponents in the 3rd District grew slightly in the latest results released Thursday, confirming that the Republican is the winner of the special election.

Lt. Gov. Spencer Cox notified the U.S. House on Thursday he could provide preliminary certification that Curtis was elected to the open seat, based on results that remain unofficial until the state's final vote canvass Nov. 21.

Curtis was already set to be sworn in Monday by U.S. House Speaker Paul Ryan, R-Wis., as Utah's newest member of Congress, but the letter from the lieutenant governor, who oversees elections for the state, makes it official.

Cox had said on election night that he saw no way for the lead to shift in the race to fill the vacancy left when former Rep. Jason Chaffetz resigned just six months into his fifth term and became a Fox News contributor.

"We wanted to see one more batch of results," the lieutenant governor said Thursday. "Sure enough, with all of the numbers we’ve seen, there’s been less than a 1-point swing."

Cox's letter cites new results from ballots counted since Election Day showing Curtis with just under 58 percent of the vote. A later update Thursday pushed Curtis just over 58 percent, up about a half a percent from Tuesday.

Curtis' nearest competitor, Democrat Kathie Allen, dropped from more than 27 percent of the vote Tuesday to just under 26 percent Thursday. The United Utah Party's Jim Bennett's share of the vote rose to more than 9 percent.

"It would appear from these unofficial results that John Curtis was elected," Cox said in the letter. "To the best of our knowledge and belief at this time, there is no contest to this election."

Cox said he conferred with the U.S. House speaker and clerk before the election about seating the winner before the outcome of the election is final. He said the results were clear enough that no further discussion was necessary.

"You're talking about 30 points," the lieutenant governor said. "There's just no reason to delay."

Especially, he said, since it's been more than four months since the 3rd District, which includes portions of Salt Lake and Utah counties, as well as Carbon, Emery, Grand, San Juan and Wasatch counties, has been represented in Congress.

Curtis will fill the remainder of Chaffetz's term. He said he will run for re-election in 2018.

Having to gear up for another run as soon as he's in office is the "terrible part of this whole thing," Curtis told participants in an "Ask Me Anything" session Thursday. He joked that his intention is not to have the shortest congressional term in Utah history.

Also tough, Curtis said, is stepping down as Provo's mayor after eight years. He said his resignation will be simultaneous to his being sworn in on the House floor at 6 p.m. Monday.

"One of my regrets is it's going so fast, I don't think I've had a chance to adequately say goodbye," Curtis said. He said the city is planning to hold a reception for him soon.

Curtis will be replaced as mayor on an acting basis by Provo City Council Chairman Dave Sewell while the council goes through the process to name an interim mayor, which requires taking applications.

But Curtis said the council is expected to choose the winner of the mayoral race to fill the slot through the end of the year. The race was decided Thursday, when Sherrie Hall Everett conceded to Michelle Kaufusi.

On election night, Everett trailed Kaufusi by 906 votes, a gap that she believed still could be closed. When that shrunk only to 881 votes Thursday, Everett said her campaign was "not seeing a strong enough trend" to overcome the gap.

On Facebook, Everett offered her congratulations to Kaufusi.

"So many have given so much to support. I love this community and the people of this community. It’s time to come together, making Provo the best it can be. That is what this race has ALWAYS been about for me. My best wishes and congratulations to Michelle Kaufusi," she wrote.

Utah County Clerk/Auditor Bryan Thompson said yet to be counted in the county are 8,000 or so ballots received in the mail Thursday and approximately 3,500 ballots that were cast provisionally.

Salt Lake County Clerk Sherrie Swensen said there are about 10,000 ballots remaining to be counted.

The next release of results by counties is set for next Tuesday, followed by an additional release if necessary on Nov. 17.

In Salt Lake County, a tie was broken in a Herriman City Council race Thursday.

Herriman District 3 candidates Cody Stromberg and Sherrie Ohrn were tied with 350 votes each, but Stromberg on Thursday gained a slight lead, 464-437.

Contributing: Katie McKellar